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Fuel Efficiency


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I know there have been some discussions about the real mpg of the RX400H compared to the published one. I just bought a pre-approved 08 400h which has just about done 10,000 miles. My fuel efficiency is only about 20-23 mpg in city driving when the traffic is smooth. Is this too low? Does the fuel efficiency increase if there is a lot of 'start stop'? Even when I drive really slowly at 10 mph, I find the engine kicking in all the time. In fact, the moment I start driving, the engine kicks in. Only when I stop pressing the accelerator, does the Battery kick in. Is this supposed to be the way? Would appreciate your comments and thoughts.

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Welcome to the joys of the 400h! ;)

In essence, you have to adapt your [driving] style to encourage the hybrid to...well drive like a hybrid. The 'lifting off' of the accelerator is something you will have to do often to encourage the batteries to kick in and if you are lucky - and can maintain a constant speed on level ground - then get about 10MINs drive time out of the hybrid Battery before, yes you guessed, it charges. In fact you will quickly see that the Battery spends more time charging than powering the car...not so good when you think that you are lugging around all that extra weight of the hybrid system.

To put it into some perspective, I [used to] get around that sort of mileage from my RX300.

Oh and welcome to the LOC!

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I agree, you do have to adjust your diving style to get the best out of the RX400H. I've had mine from new since last September and currently have about 17000 miles on the clock, at the moment i can get around 30-32 on average out of evey tank of fuel. On the motorway, and I do a lot of the motorway, at a steady 70mph I have got upto just over 34mpg. Around town it does drop but once the car has warmed up I find I can get use out of the batteries if I am careful, stop start can be mostly Battery if in traffic. However, for all the reasons that other people have stated I still love the car and it still gives me a big smile everytime I get in and go somehwere.

Enjoy the car/SUV/4x4 ish.

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That MPG figure is too low.

Even when I drive to the Dordogne in France, exactly 680 miles door to door, the car still averages 28MPG. Every day use in London traffic returns 30 - 32 MPG. I have had three of these vehicles, each averaging 20,000 miles per year and have never had MPG dropping below 28MPG. It is true you have to adapt your driving style, but that does not mean you have to drive at snails pace.

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That MPG figure is too low.

Even when I drive to the Dordogne in France, exactly 680 miles door to door, the car still averages 28MPG. Every day use in London traffic returns 30 - 32 MPG. I have had three of these vehicles, each averaging 20,000 miles per year and have never had MPG dropping below 28MPG. It is true you have to adapt your driving style, but that does mean you have to drive at snails pace.

Where's the fun in that ? B)

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That MPG figure is too low.

Even when I drive to the Dordogne in France, exactly 680 miles door to door, the car still averages 28MPG. Every day use in London traffic returns 30 - 32 MPG. I have had three of these vehicles, each averaging 20,000 miles per year and have never had MPG dropping below 28MPG. It is true you have to adapt your driving style, but that does mean you have to drive at snails pace.

Where's the fun in that ? B)

Sorry - It was meant to say "that does NOT mean you have to drive at snails pace"!

French autoroutes are not known for hosting slow drivers!!

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In that case, I have to admit I am quite impressed. How on earth are you managing 30 - 32 mpg in London ? I seem to only ever average 22mpg and have come to accept it as par for the course. Pray tell in what way(s) specifically have you adapted your driving style ?

Thanks in advance

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I am in a similar position to mama mia in that I bought an 08 plate 400h SE in December 08 with around 9,500 miles on the clock.

I have done 6000 miles so far and average 30.8 mpg. Mostly motorway driving with cruise control set at 75mph. I had a couple of minor problems with the vehicle and received a replacement 400h for a day. I drove it like an 18 year old.... flooring it at every set of traffic lights and motorway driving at 85-90mph (not legal but not a ban) and averaged 27mpg - however I was not in any traffic jams.

400h ownership is great. There are detractors but it is a great all-rounder.

This site is great too. Thanks for all the advice to date.

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In that case, I have to admit I am quite impressed. How on earth are you managing 30 - 32 mpg in London ? I seem to only ever average 22mpg and have come to accept it as par for the course. Pray tell in what way(s) specifically have you adapted your driving style ?

Thanks in advance

I don't do anything special. I try to keep the car rolling as often as possible, controlling the speed using the accelerator by anticipating events and potential obstacles as far ahead as possible so that I can slow the car down gradually rather than rushing towards traffic lights or slow moving traffic and then being forced to use the breaks. I use the same approach on motorways and often manage to drive anti-clockwise from Junction 13 of the M25 to the Folkestone Eurotunnel exit without touching the brakes.

I find that when the Battery is fully charged the car will run at 40miles per hour for quite a distance. In london traffic, the car spends most of the time running on Battery power and then re-charging when the traffic comes to a stand still. Not using the Air Conditioning also helps in Winter. I suppose it also depends upon how your Battery charges - I can get often get mine to charge to full green bars as I descend down a steep hill towards the village I live in.

I also only use premium unleaded from Shell wherever possible and BP on other occasions.

When I had a MkII RX300, I used to average 20-22mpg for every day driving, and 25-27mpg on longer runs.

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I also only use premium unleaded from Shell wherever possible and BP on other occasions.

I think premium fuel may make a difference. It didn't make such a difference in the RX300 I had, but I have heard other reports that the 400h responds better to the premium fuel...so if in addition you amend your driving style (as described) then you can increase the MPG by a couple for sure. But in my (albeit limited) experience of running a 400h, you really have to make a conscious effort to adjust your driving style and this yields better results than just premium fuel by itself.

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I find that when the battery is fully charged the car will run at 40miles per hour for quite a distance. In london traffic, the car spends most of the time running on battery power and then re-charging when the traffic comes to a stand still.

This is a very good point: as the 400h 'breaks in' it is possible to extend the barrier of Battery only running. This means it is possible to run ~ 40MPH on Battery alone. But the Hybrid Battery provides only 10MINs (or so) worth of running. I can't see it providing much more. To me the Hybrid Battery spends a disproportionate time charging...

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In that case, I have to admit I am quite impressed. How on earth are you managing 30 - 32 mpg in London ? I seem to only ever average 22mpg and have come to accept it as par for the course. Pray tell in what way(s) specifically have you adapted your driving style ?

Thanks in advance

I don't do anything special. I try to keep the car rolling as often as possible, controlling the speed using the accelerator by anticipating events and potential obstacles as far ahead as possible so that I can slow the car down gradually rather than rushing towards traffic lights or slow moving traffic and then being forced to use the breaks. I use the same approach on motorways and often manage to drive anti-clockwise from Junction 13 of the M25 to the Folkestone Eurotunnel exit without touching the brakes.

I find that when the Battery is fully charged the car will run at 40miles per hour for quite a distance. In london traffic, the car spends most of the time running on Battery power and then re-charging when the traffic comes to a stand still. Not using the Air Conditioning also helps in Winter. I suppose it also depends upon how your Battery charges - I can get often get mine to charge to full green bars as I descend down a steep hill towards the village I live in.

I also only use premium unleaded from Shell wherever possible and BP on other occasions.

When I had a MkII RX300, I used to average 20-22mpg for every day driving, and 25-27mpg on longer runs.

Thanks for the tips. I am going to try it. Today, I took the car on the highway and the average I did was only 27 MPG - which is far from satisfactory. I also find that I cannot sufficiently get the Battery to be charged to the maximum green bars. The highest it can go is 2 to 3 bars above the mid-point. How can I get it fully charged without the benefit of going down slopes? should I get the car checked? Many thanks!!

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I am in a similar position to mama mia in that I bought an 08 plate 400h SE in December 08 with around 9,500 miles on the clock.

I have done 6000 miles so far and average 30.8 mpg. Mostly motorway driving with cruise control set at 75mph. I had a couple of minor problems with the vehicle and received a replacement 400h for a day. I drove it like an 18 year old.... flooring it at every set of traffic lights and motorway driving at 85-90mph (not legal but not a ban) and averaged 27mpg - however I was not in any traffic jams.

400h ownership is great. There are detractors but it is a great all-rounder.

This site is great too. Thanks for all the advice to date.

That's great efficiency. Does it mean that the efficients speed is more than 85 mph?

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I'll be sure to give those a try but I have to say I'm not convinced. As others have commented, a large proportion of time seems to be spent charging the Battery, the real benefits of Battery power seem to be in stop start traffic; that being said even London traffic has not been enough to boost my mpg

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I'll be sure to give those a try but I have to say I'm not convinced. As others have commented, a large proportion of time seems to be spent charging the battery, the real benefits of battery power seem to be in stop start traffic; that being said even London traffic has not been enough to boost my mpg

Hi new member here as well i recently bought and 05 400h se-L it has done 50k ish and driving in a 'hybrid style' I got almost 38MPG (i have a picture of it somewhere), but I couldnt handle driving like this for more than one tank of fuel I was starting not to enjoy driving.

but even driving like I used to drive my CLK I still get 33 MPG out of it

so maybe it is about the engine and Battery doing enough miles to optimize performance.

Any tips about where to go for servicing I live/ in South East/ East London

and what would I be looking at with a 60k service? £ wise?

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Interesting thread!

I got a new 400h yesterday - only 4 miles on the clock. I am in West Yorkshire and commute in and out of Bradford in heavy traffic. So far, my average is 31 mpg in 50 miles - engine no way near "run in" yet of course! Coming out of RX300 and 350, seeing mpg that starts with a 3x, and from crawling in traffic, is simply wierd, but great at the same time.

I always thought that at speeds above about 20mph, the 400h would switch to petrol mode. Completely wrong! Today I have been driving (on the flat) for a couple of miles at a time doing 30-40mph on Battery only. I am sure the novelty will wear off, but 1 day into ownership and I am finding it wonderful and amazing. It is smooth, quiet, and more than adequate power getting off the line (but I am treating it gently right now). Loving it.

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...driving in a 'hybrid style' I got almost 38MPG (i have a picture of it somewhere)

The ONLY way of talking reliable figures would be to use figures from a brim-to-brim fill up. Otherwise relying on the OBC you will find that you will also ahcieve 99.9MPG in certain situations - if you beleive that, then well I guess the moon is also made out of cheese and the Earth is indeed flat.

Talking OBC is pointless IMHO.

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...driving in a 'hybrid style' I got almost 38MPG (i have a picture of it somewhere)

The ONLY way of talking reliable figures would be to use figures from a brim-to-brim fill up. Otherwise relying on the OBC you will find that you will also ahcieve 99.9MPG in certain situations - if you beleive that, then well I guess the moon is also made out of cheese and the Earth is indeed flat.

Talking OBC is pointless IMHO.

Fair play but how far off would it be?

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...driving in a 'hybrid style' I got almost 38MPG (i have a picture of it somewhere)

The ONLY way of talking reliable figures would be to use figures from a brim-to-brim fill up. Otherwise relying on the OBC you will find that you will also ahcieve 99.9MPG in certain situations - if you beleive that, then well I guess the moon is also made out of cheese and the Earth is indeed flat.

Talking OBC is pointless IMHO.

We are talking averages here though aren't we? 99.9 mpg would be an example of instantaneous consumption like coming down a steep hill and no gas is being consumed. Brim to brim would be more accurate per se, but the onboard computers should not vary from car to car (unless potentially running different software versions) - so it provides a useful comparison from car to car experiences.

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Fair play but how far off would it be?

Well, it all depends if you really truly want to know - my RX used to be about +/-3MPG depending ;)

It really is inaccurate and inadviseable to use as a comparitor in any shape or form. It is jsut a rough indicator, but hey if you're happy to accept what it tells you then thats fine too. We all have a chuckle at those LED astray by their SatNav systems - this is no different.

Noticed how in the 400h there is no 'miles left' counter as there is in the petrol RX?

If you want the brutal truth, brim-to-brim folks. Anything else is just pure fantasy.

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We are talking averages here though aren't we? 99.9 mpg would be an example of instantaneous consumption like coming down a steep hill and no gas is being consumed. Brim to brim would be more accurate per se, but the onboard computers should not vary from car to car (unless potentially running different software versions) - so it provides a useful comparison from car to car experiences.

But the point about using a comparitor is to ensure it is initself accurate. OBCs are only indicative and can vary. Brim-to-brim is the only way to draw a comparitor between models as it is fool proof and decidedly accurate.

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We are talking averages here though aren't we? 99.9 mpg would be an example of instantaneous consumption like coming down a steep hill and no gas is being consumed. Brim to brim would be more accurate per se, but the onboard computers should not vary from car to car (unless potentially running different software versions) - so it provides a useful comparison from car to car experiences.

But the point about using a comparitor is to ensure it is initself accurate. OBCs are only indicative and can vary. Brim-to-brim is the only way to draw a comparitor between models as it is fool proof and decidedly accurate.

Even brim to brim comparisons can be inaccurate.

It all depends on how patient you are at the pump. (Or indeed whether or not you use the same pump every time or yet again depending on the ambient temperature, etc etc.) The difference between the first click off of the pump and petrol actually overflowing over the edge of the filler neck can be up to 10 litres!!!

A more accurate way is to keep a log of fuel bought and miles driven over, say, 5000 miles to iron out the different inaccuracies. But then you only get an overall figure which doesn't tell you consumption for different types of journey in different temperatures.

I still say the biggest variable is the right foot!!!!

JBP

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A more accurate way is to keep a log of fuel bought and miles driven over, say, 5000 miles to iron out the different inaccuracies. But then you only get an overall figure which doesn't tell you consumption for different types of journey in different temperatures.

I still say the biggest variable is the right foot!!!!

JBP

How unbelievably dull an existence would you have to lead to actually do that !

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